The present invention relates to placement of sensors within a patient's body, and in particular relates to facilitating repeated placement of a non-sterile sensor, such as an ultrasound transducer, into a patient's body in a minimally invasive and sterile manner.
It is frequently desirable to obtain information regarding the size, shape, and function of internal body organs by the use of ultrasound echo imaging. For example, it is desirable to evaluate the performance of a patient's heart after cardiac surgery. In the time immediately after such surgery, patients frequently have significant cardiac functional problems, and visualization and examination of the heart by ultrasound echo imaging may be of critical value. Currently, transthoracic and transesophageal echocardiography are performed as manners of observing the heart. These are not entirely desirable, however, as the second requires sedation and presents risks of trauma to the esophagus and the images obtained by the first are of poor quality after cardiac surgery.
Fonger et al. U.S. Pat. No. 5,291,896 discloses a sterile cardiac probe inserted through an open-ended lumen of a flexible chest drain tube having one end extending into the thoracic cavity of a patient. The probe is surgically fastened to the aorta or the pulmonary artery of the patient in order to obtain information relating only to the volume of flow of blood through such vessels.
Czar et al. U.S. Pat. No. 5,205,292 discloses a removable surgically implanted sterile transducer for attachment to a blood vessel in order to evaluate the volume of blood flow in the vessel.
Abrams et al. U.S. Pat. No. 4,671,295 discloses a method and apparatus for measuring cardiac output through the use of a transducer introduced into the patient's trachea to transmit and receive ultrasound waves and evaluate the flow of blood in the ascending aorta through the use of Doppler frequency differences.
Weber U.S. Pat. No. 4,886,059 discloses an endotracheal tube including a transducer assembly disposed to transmit ultrasound waves in selected directions through the tracheal wall to collect Doppler data for blood flow velocity calculation and to calculate the diameter of the artery.
None of the devices disclosed in the patents discussed above, however, provides for placement of a non-sterile sensor such as an ultrasound transducer in a desired position within a sterile body cavity of a patient quickly, easily and repeatedly, nor does any of them provide a way of obtaining scanned ultrasound two-dimensional echo images of internal organs without having to transmit the ultrasound waves into the body from an external location.
What is desired, then, is a device and a method for its use in permitting a non-sterile sensor such as an ultrasound scanning transducer to be introduced into a body cavity of a patient quickly and easily in a sterile fashion, and without performing additional surgical procedures or sedation as part of the introduction of the transducer. It is also desired to provide for removal and later temporary reintroduction of a non-sterile sensor without further surgical procedures or sedation.